1. Field of the Invention
The present invention relates generally to the design of tubular sports implements, such as baseball bats or golf club shafts, and more particularly to such an instrument which is designed to reduce unwanted vibration in the implement and to increase the hitting effectiveness of the instrument.
2. Description of the Prior Art
There have been a number of attempts in the prior art to reduce unwanted vibrations in implements such as bats and golf clubs. One such example is that shown in U.S. Pat. No. 5,711,728 to Marcello, which describes a wooden ball bat having externally protruding ridges or knurls above the handle of the bat.
Another approach is shown in U.S. Pat. No. 5,772,541 to Bujatti which discloses the use of an elastomeric vibration damping member which is freely movable within a chamber defined on the implement.
U.S. Pat. No. 5,759,113 to Lai et al. discloses the use of longitudinal strips of visco-elastic damping material.
U.S. Pat. No. 3,941,380 to Lacoste and U.S. Pat. No. 5,655,980 to Nashif et al. both disclose the use,of cantilevered vibrational damping devices.
U.S. Pat. No. 1,509,733 to Langford discloses a two piece wooden bat having an elastomeric damping ring located between the two sections.
U.S. Pat. No. 5,624,114 to Kelsey discloses a ball bat shock dampener which attaches to the knob end of the bat.
U.S. Pat. No. 5,842,933 to Lewis discloses a grip for a golf club or the like having a built in shock absorber comprised of an elastomeric plug received in the handle end of the implement and attached to the external grip.
U.S. Pat. No. 5,692,971 to Williams discloses a shock absorbing insert for use in a golf club or the like.
Thus, it is seen that there is a continuing desire in the art to find improved techniques for tuning the vibrational response of a ball bat, golf club or other such sports implement utilized to strike a ball. The present invention provides a new and improved technique for accomplishing such a result.
A tuned sports implement is provided which includes an impact portion constructed to impact a ball, a handle portion constructed to be held by a human hand, a hollow structural member including an outer wall defining an interior space, the structural member connecting the impact portion and the handle portion, and a structural bridge received in the interior space of the structural member and attached to the outer wall. The structural characteristics of the bridge are selected to reduce wasted bending energy and increase energy transfer between the implement and the ball.
Preferably, the handle and impact portions are hollow and are integral portions of the structural member.
In one embodiment, the structural member is a bat constructed of aluminum.
The structural bridge may be attached to the wall be several means. One technique for attaching the structural bridge to the internal surface of the wall is by adhesive. The adhesive will provide a means for dampening vibration of the implement upon striking a ball.
Another technique for attaching the bridge to the wall of the implement is by welding the bridge to the implement.
When the improvements of the present invention are applied to the design of a baseball bat, it results in a bat in which the size of the sweet spot of the bat is increased.
The structural characteristics of the bridge are selected to reduce the amount of energy which is transferred into the first and second vibrational modes of the bat, and to increase the amount of energy in the third vibrational mode of the bat. Because of the bridge, resonance interaction between the bat and the ball is increased.
The invention may also be described as a hollow aluminum ball bat including a handle portion, a barrel portion having a circumferential outer wall, a transition portion joining the handle portion and the barrel portion, and a structural bridge located within the barrel portion and attached to and spanning the circumferential outer wall.
It is therefore an object of the present invention to provide an improved sports implement in which the amount of energy transferred from the implement to a ball struck by the implement is increased.
Still another object of the present invention is the provision of a tubular sports implement having a structural bridge received therein for modifying the vibration characteristics of the implement.
Still another object of the present invention is the provision of a sports implement having reduced vibration in the handle when the implement strikes a ball.
Still another object of the present invention is the provision of a ball bat having an enlarged sweet spot.
And yet another object of the present invention is the provision of a sports implement which has a resonance interaction between the implement and a ball which is struck by the instrument.
And another object of the present invention is the provision of a sports implement constructed to tune the implement""s third vibrational mode to that corresponding to a ball to be used with the instrument.